Sialyl Lewis x (sLex) carbohydrate antigen acts as an adhesion molecule expressed on the surface of cancer cells and is the most important ligand of the selectins present on endothelial cells. sLex expression was correlated to the metastatic potential of breast cancer. The aim of the present work was to evaluate the prognostic value of sLex in a series of breast carcinomas with long-term follow-up. A total of 127 consecutive patients with primary breast cancer were enrolled and followed for a median of 140 months. Tumor grade, mitotic index, histotype, vascular invasion, and tumor extension and sLex were recorded and used in multivariate analysis. sLex antigen was expressed in 37 specimens (21%). Survival was similar for sLex-positive and sLex-negative tumors (62% vs 60%) for overall survival and for disease-free survival (59% vs 56%). Expression of sLex antigen in breast cancer is not associated with breast cancer survival.